1. Field of the Invention
The present invention relates to a method and an apparatus adapted to prepare coded signals indicative of images of three or more colors of a subject copy, for transmission to a remote apparatus such as a remote facsimile receiver, for reproduction of the subject copy, and an apparatus operable to effect a recording on different types of recording medium, based on such coded signals.
2. Discussion of the Prior Art
An example of such a signal transmission method as indicated above is disclosed in Publication No. 60-31388 of examined Japanese Patent Application (published for opposition purpose), wherein run-length code data indicative of black and white images of a subject copy, which is prepared for delivery to a remote recording apparatus, is utilized to transmit images of another color such as a red color. According to the disclosed method, a red-colored area along a line of original images is represented by a run-length code indicative of the length of the red-colored area, and a flag code and a one-bit control code which precede that run-length code. The flag code is indicative of the red color, while the one-bit control code indicates whether the run-length code of the red-colored area is prepared based on the run-length coding for the black images or run-length coding for white images. The flag code is a run-length code which is usually never used, for instance, the run-length code representative of the run-length of "0" of a black-colored area.
Also, laid-open Publication No. 61-123281 of unexamined Japanese Patent Application discloses a method adapted for transmission of a four-color subject copy which includes green and red images other than black and white images. This method is based on a proposition that run-length codes for the white images and run-length codes for the black images are transmitted alternately. The green and red images are represented by flag codes which are combinations of the run-length code for the run length of "0" of a white colored area, and the run-length codes for black-colored areas. The flag codes represent the green-and red-colored areas, depending upon which one of the two codes of each flag code precedes the other or comes first.
The methods proposed in the above-identified publications are effective to reduce the volume of data that should be transmitted, and permit the transmission of a subject copy involving images of three or more colors, in a relatively short period of time. However, the volumetric reduction of the required image transmission data according to the proposed method is still insufficient. For example, even where a line of original images consisting of only white and red images (i.e., red images on a white background color of a subject copy sheet), run-length codes for red-colored areas should always be preceded by flag codes that indicate that the following run-length codes are those for the red-colored areas. Accordingly, the overall volume of the image data to be transmitted tends to be large.
On the other hand, laid-open Publication No. 57-119567 proposes to further reduce the volume of the required image data, by using a color-shift code only when the color of the image areas is changed. For instance, the color-shift code may be the run-length code representative of the run length of "0" of a white- or black-colored area, or a combination of these two run-length codes.
The method according to the above proposal does not require each of the run-length codes for red-colored areas to be accompanied by an appropriate flag code which indicates that the run-length code is that for a red-colored area. Accordingly, a further volumetric reduction of the required image data is achieved.
Usually, a recording apparatus such as a remote facsimile receiver which effects a recording based on received image signals such as run-length code data as described above is operated in different modes depending upon types of a recording medium. For example, a thermo-sensitive recording medium has one or more coloring layers formed on a substrate. Each coloring layer is colored when heated to a predetermined temperature, whereby a recording is accomplished by selectively heating local areas or spots on the medium. The coloring layers corresponding to two or more colors other than the background color (usually whitish color) of the medium have different coloring temperatures. Namely, the amounts of thermal energy necessary to color the different coloring layers are different. Therefore, the recording of images in desired colors requires the use of a thermo-sensitive medium having appropriate coloring layers, and the heating of these coloring layers with necessary amounts of thermal energy. To this end, the recording apparatus should have different operation modes depending upon the specific types of the thermo-sensitive recording medium.
A recording apparatus capable of receiving different types of thermo-sensitive recording medium as indicated above is known. For example, there is known a facsimile apparatus "RIFAX 810SR" available from RICOH (a Japanese manufacturer) which is operable in a black-and-red mode in which both black and red images can be recorded, as well as in a black mode in which only black images can be recorded. In this facsimile apparatus, the recording of black images is effected on a thermo-sensitive paper which has a black coloring layer on a substrate, while the recording in black and red colors is effected on a thermo-sensitive paper having a black coloring layer and a red coloring layer. The recording device of the apparatus operates in the two different modes which are selected depending upon the type of the paper currently used, so that the coloring layer or layers may be heated with the appropriate amount or amounts of thermal energy necessary to effect the intended recording operation in the desired color or colors.
The facsimile apparatus indicated above has a cavity or space provided in the apparatus body for accommodating a roll of the desired one of the two types of a thermo-sensitive web. The opening leading to the cavity is usually closed by a pivotable top cover, whereby the roll of web is not visible from the outside during the use of the apparatus. With the roll of the desired type of the thermo-sensitive web set in position, the recording device is placed in one of the two recording modes that suits the currently used type of the web. The recording modes are established or changed by using a plurality of keys on an operator's control panel provided on the outer surface of the apparatus body.
Certainly, the keys on the control panel serve the other purposes for controlling the apparatus. Therefore, when the recording web is changed from one type to the other, the keys must be operated repeatedly in the predetermined order. Thus, the procedure to control the apparatus is difficult to understand and cumbersome, and may be erroneously performed. This problem generally exists in a recording apparatus which selectively uses different types of recording medium (e.g., different sizes of medium) and which is operated in the correspondingly selected different modes.